Early ventilation and outcome in patients with moderate to severe traumatic brain injury

Advanced Critical Care Techniques in the Field

Critical care principles and techniques continue to hold promise for improving patient outcomes in time-dependent diseases encountered by emergency medical services such as cardiac arrest, acute ischemic stroke, and hemorrhagic shock. In this review, the authors discuss several current and evolving advanced critical care modalities, including extracorporeal cardiopulmonary resuscitation, resuscitative endovascular occlusion of the aorta, prehospital thrombolytics for acute ischemic stroke, and low-titer group O whole blood for trauma patients. Two important critical care monitoring technologies-capnography and ultrasound-are also briefly discussed.

EMS Treatment Guidelines in Major Traumatic Brain Injury With Positive Pressure Ventilation

Importance

The Excellence in Prehospital Injury Care (EPIC) study demonstrated improved survival in patients with severe traumatic brain injury (TBI) following implementation of the prehospital treatment guidelines. The impact of implementing these guidelines in the subgroup of patients who received positive pressure ventilation (PPV) is unknown.

Objective

To evaluate the association of implementation of prehospital TBI evidence-based guidelines with survival among patients with prehospital PPV.

Design, Setting, and Participants

The EPIC study was a multisystem, intention-to-treat study using a before/after controlled design. Evidence-based guidelines were implemented by emergency medical service agencies across Arizona. This subanalysis was planned a priori and included participants who received prehospital PPV. Outcomes were compared between the preimplementation and postimplementation cohorts using logistic regression, stratified by predetermined TBI severity categories (moderate, severe, or critical). Data were collected from January 2007 to June 2017, and data were analyzed from January to February 2023.

Exposure

Implementation of the evidence-based guidelines for the prehospital care of patient with TBI.

Main Outcomes and Measures

The primary outcome was survival to hospital discharge, and the secondary outcome was survival to admission.

Results

Among the 21 852 participants in the main study, 5022 received prehospital PPV (preimplementation, 3531 participants; postimplementation, 1491 participants). Of 5022 included participants, 3720 (74.1%) were male, and the median (IQR) age was 36 (22-54) years. Across all severities combined, survival to admission improved (adjusted odds ratio [aOR], 1.59; 95% CI, 1.28-1.97), while survival to discharge did not (aOR, 0.94; 95% CI, 0.78-1.13). Within the cohort with severe TBI but not in the moderate or critical subgroups, survival to hospital admission increased (aOR, 6.44; 95% CI, 2.39-22.00), as did survival to discharge (aOR, 3.52; 95% CI, 1.96-6.34).

Conclusions and Relevance

Among patients with severe TBI who received active airway interventions in the field, guideline implementation was independently associated with improved survival to hospital admission and discharge. This was true whether they received basic airway interventions or advanced airways. These findings support the current guideline recommendations for aggressive prevention/correction of hypoxia and hyperventilation in patients with severe TBI, regardless of which airway type is used.

Feasibility of quality indicators on prehospital advanced airway management in a physician-staffed emergency medical service: survey-based assessment of the provider point of view

OBJECTIVE

We aimed to determine the feasibility of quality indicators (QIs) for prehospital advanced airway management (PAAM) from a provider point of view.

DESIGN

The study is a survey based feasibility assessment following field testing of QIs for PAAM.

SETTING

The study was performed in two physician staffed emergency medical services in Switzerland.

PARTICIPANTS

42 of the 44 emergency physicians who completed at least one case report form (CRF) dedicated to the collection of the QIs on PAAM between 1 January 2019 and 31 December 2021 participated in the study.

INTERVENTION

The data required to calculate the 17 QIs was systematically collected through a dedicated electronic CRF.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcomes were provider-related feasibility criteria: relevance and acceptance of the QIs, as well as reliability of the data collection. Secondary outcomes were effort to collect specific data and to complete the CRF.

RESULTS

Over the study period, 470 CRFs were completed, with a median of 11 per physician (IQR 4-17; range 1-48). The median time to complete the CRF was 7 min (IQR 3-16) and was considered reasonable by 95% of the physicians. Overall, 75% of the physicians assessed the set of QIs to be relevant, and 74% accepted that the set of QIs assessed the quality of PAAM. The reliability of data collection was rated as good or excellent for each of the 17 QIs, with the lowest rated for the following 3 QIs: duration of preoxygenation, duration of laryngoscopy and occurrence of desaturation during laryngoscopy.

CONCLUSIONS

Collection of QIs on PAAM appears feasible. Electronic medical records and technological solutions facilitating automatic collection of vital parameters and timing during the procedure could improve the reliability of data collection for some QIs. Studies in other services are needed to determine the external validity of our results.

Trending Ability of End-Tidal Capnography Monitoring During Mechanical Ventilation to Track Changes in Arterial Partial Pressure of Carbon Dioxide in Critically Ill Patients With Acute Brain Injury: A Monocenter Retrospective Study

BACKGROUND

Changes in arterial partial pressure of carbon dioxide (Pa co2 ) may alter cerebral perfusion in critically ill patients with acute brain injury. Consequently, international guidelines recommend normocapnia in mechanically ventilated patients with acute brain injury. The measurement of end-tidal capnography (Et co2 ) allows its approximation. Our objective was to report the agreement between trends in Et co2 and Pa co2 during mechanical ventilation in patients with acute brain injury.

METHODS

Retrospective monocenter study was conducted for 2 years. Critically ill patients with acute brain injury who required mechanical ventilation with continuous Et co2 monitoring and with 2 or more arterial gas were included. The agreement was evaluated according to the Bland and Altman analysis for repeated measurements with calculation of bias, and upper and lower limits of agreement. The directional concordance rate of changes between Et co2 and Pa co2 was evaluated with a 4-quadrant plot. A polar plot analysis was performed using the Critchley methods.

RESULTS

We analyzed the data of 255 patients with a total of 3923 paired ΔEt co2 and ΔPa co2 (9 values per patient in median). Mean bias by Bland and Altman analysis was -8.1 (95 CI, -7.9 to -8.3) mm Hg. The directional concordance rate between Et co2 and Pa co2 was 55.8%. The mean radial bias by polar plot analysis was -4.4° (95% CI, -5.5 to -3.3) with radial limit of agreement (LOA) of ±62.8° with radial LOA 95% CI of ±1.9°.

CONCLUSIONS

Our results question the performance of trending ability of Et co2 to track changes in Pa co2 in a population of critically ill patients with acute brain injury. Changes in Et co2 largely failed to follow changes in Pa co2 in both direction (ie, low concordance rate) and magnitude (ie, large radial LOA). These results need to be confirmed in prospective studies to minimize the risk of bias.

Agreement between arterial and end-tidal carbon dioxide in adult patients admitted with serious traumatic brain injury

BACKGROUND

Low-normal levels of arterial carbon dioxide (PaCO2) are recommended in the acute phase of traumatic brain injury (TBI) to optimize oxygen and CO2 tension, and to maintain cerebral perfusion. End-tidal CO2 (ETCO2) may be used as a surrogate for PaCO2 when arterial sampling is less readily available. ETCO2 may not be an adequate proxy to guide ventilation and the effects on concomitant injury, time, and the impact of ventilatory strategies on the PaCO2-ETCO2 gradient are not well understood. The primary objective of this study was to describe the correlation and agreement between PaCO2 and ETCO2 in intubated adult trauma patients with TBI.

METHODS

This study was a retrospective analysis of prospectively-collected data of intubated adult major trauma patients with serious TBI, admitted to the East of England regional major trauma centre; 2015-2019. Linear regression and Welch's test were performed on each cohort to assess correlation between paired PaCO2 and ETCO2 at 24-hour epochs for 120 hours after admission. Bland-Altman plots were constructed at 24-hour epochs to assess the PaCO2-ETCO2 agreement.

RESULTS

695 patients were included, with 3812 paired PaCO2 and ETCO2 data points. The median PaCO2-ETCO2 gradient on admission was 0.8 [0.4-1.4] kPa, Bland Altman Bias of 0.96, upper (+2.93) and lower (-1.00), and correlation R2 0.149. The gradient was significantly greater in patients with TBI plus concomitant injury, compared to those with isolated TBI (0.9 [0.4-1.5] kPa vs. 0.7 [0.3-1.1] kPa, p<0.05). Across all groups the gradient reduced over time. Patients who died within 30 days had a larger gradient on admission compared to those who survived; 1.2 [0.7-1.9] kPa and 0.7 [0.3-1.2] kPa, p<0.005.

CONCLUSIONS

Amongst adult patients with TBI, the PaCO2-ETCO2 gradient was greater than previously reported values, particularly early in the patient journey, and when associated with concomitant chest injury. An increased PaCO2-ETCO2 gradient on admission was associated with increased mortality.

Impact of Hypo- and Hyper-capnia on Spreading Depolarizations in Rat Cerebral Cortex

Patients with traumatic brain injury are typically maintained at low-normal levels of arterial partial pressure of carbon dioxide (PaCO2) to counteract the risk of elevated intracranial pressure during intensive care. However, several studies suggest that management at hypercarbic levels may have therapeutic benefit. Here we examined the impact of CO2 levels on spreading depolarizations (SD), a mechanism and marker of acute lesion development in stroke and brain trauma. In an acute preparation of mechanically ventilated (30/70 O2/N2) female rats, SDs were evoked by cortical KCl application and monitored by electrophysiology and laser doppler flowmetry; CO2 levels were adjusted by ventilator settings and supplemental CO2. During 90 min of KCl application, rats were maintained at hypocapnia (end-tidal CO2 22 ± 2 mmHg) or hypercapnia (57 ± 4 mmHg) but did not differ significantly in arterial pH (7.31 ± 0.10 vs. 7.22 ± 0.08, p = 0.31) or other variables. Surprisingly, there was no difference between groups in the number of SDs recorded (10.7 ± 4.2 vs. 11.7 ± 3.1; n = 3 rats/group; p = 0.75) nor in SD durations (64 ± 27 vs. 69 ± 37 sec, p = 0.54). In separate experiments (n = 3), hypoxia was induced by decreasing inhaled O2 to 10% and single SDs were induced under interleaved conditions of hypo-, normo-, and hypercapnia. No differences in SD duration were observed. In both normoxia and hypoxia experiments, however, mean arterial pressures were negatively correlated with SD durations (normoxia R2 = -0.29; hypoxia R2 = -0.61, p's < 0.001). Our results suggest that any therapeutic benefit of elevated CO2 therapy may be dependent on an acidic shift in pH or may only be observed in conditions of focal brain injury.

Pre-hospital endotracheal intubation in severe traumatic brain injury: ventilation targets and mortality-a retrospective analysis of 308 patients

BACKGROUND

Traumatic brain injury (TBI) remains one of the main causes of mortality and long-term disability worldwide. Maintaining physiology of brain tissue to the greatest extent possible through optimal management of blood pressure, airway, ventilation, and oxygenation, improves patient outcome. We studied the quality of prehospital care in severe TBI patients by analyzing adherence to recommended target ranges for ventilation and blood pressure, prehospital time expenditure, and their effect on mortality, as well as quality of prehospital ventilation assessed by arterial partial pressure of CO2 (PaCO2) at hospital admission.

METHODS

This is a retrospective cohort study of all TBI patients requiring tracheal intubation on scene who were transported to one of two major level 1 trauma centers in Switzerland between January 2014 and December 2019 by Swiss Air Rescue (Rega). We assessed systolic blood pressure (SBP), end-tidal partial pressure of CO2 (PetCO2), and PaCO2 at hospital admission as well as prehospital and on-scene time. Quality markers of prehospital care (PetCO2, SBP, prehospital times) and prehospital ventilation (PaCO2) are presented as descriptive analysis. Effect on mortality was calculated by multivariable regression analysis and a logistic general additive model.

RESULTS

Of 557 patients after exclusions, 308 were analyzed. Adherence to blood pressure recommendations was 89%. According to PetCO2, 45% were normoventilated, and 29% had a SBP ≥ 90 mm Hg and were normoventilated. Due to the poor correlation between PaCO2 and PetCO2, only 33% were normocapnic at hospital admission. Normocapnia at hospital admission was strongly associated with reduced probability of mortality. Prehospital and on-scene times had no impact on mortality.

CONCLUSIONS

PaCO2 at hospital admission is strongly associated with mortality risk, but normocapnia is achieved only in a minority of patients. Therefore, the time required for placement of an arterial cannula and prehospital blood gas analysis may be warranted in severe TBI patients requiring on-scene tracheal intubation.

The European guideline on management of major bleeding and coagulopathy following trauma: sixth edition

BACKGROUND

Severe trauma represents a major global public health burden and the management of post-traumatic bleeding continues to challenge healthcare systems around the world. Post-traumatic bleeding and associated traumatic coagulopathy remain leading causes of potentially preventable multiorgan failure and death if not diagnosed and managed in an appropriate and timely manner. This sixth edition of the European guideline on the management of major bleeding and coagulopathy following traumatic injury aims to advise clinicians who care for the bleeding trauma patient during the initial diagnostic and therapeutic phases of patient management.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma included representatives from six European professional societies and convened to assess and update the previous version of this guideline using a structured, evidence-based consensus approach. Structured literature searches covered the period since the last edition of the guideline, but considered evidence cited previously. The format of this edition has been adjusted to reflect the trend towards concise guideline documents that cite only the highest-quality studies and most relevant literature rather than attempting to provide a comprehensive literature review to accompany each recommendation.

RESULTS

This guideline comprises 39 clinical practice recommendations that follow an approximate temporal path for management of the bleeding trauma patient, with recommendations grouped behind key decision points. While approximately one-third of patients who have experienced severe trauma arrive in hospital in a coagulopathic state, a systematic diagnostic and therapeutic approach has been shown to reduce the number of preventable deaths attributable to traumatic injury.

CONCLUSION

A multidisciplinary approach and adherence to evidence-based guidelines are pillars of best practice in the management of severely injured trauma patients. Further improvement in outcomes will be achieved by optimising and standardising trauma care in line with the available evidence across Europe and beyond.

Higher Oxygenation Is Associated with Improved Survival in Severe Traumatic Brain Injury but Not Traumatic Shock

Pre-hospital resuscitation of critically injured patients traditionally includes supplemental oxygen therapy to address potential hypoxemia. The objective of this study was to explore the association between pre-hospital hypoxemia, hyperoxemia, and mortality in patients with traumatic brain injury (TBI) and traumatic shock. We hypothesized that both hypoxemia and hyperoxemia would be associated with increased mortality. We used the Resuscitation Outcomes Consortium Prospective Observational Prehospital and Hospital Registry for Trauma (ROC PROPHET) database of critically injured patients to identify a severe TBI cohort (pre-hospital Glasgow Coma Scale [GCS] 3-8) and a traumatic shock cohort (systolic blood pressure ≤90 mm Hg and pre-hospital GCS >8). Arterial blood gas (ABG) obtained within 30 min of hospital arrival was required for inclusion. Patients with hypoxemia (PaO₂ <80 mm Hg) and hyperoxemia (PaO₂ >400 mm Hg) were compared to those with normoxemia (PaO₂ 80-400 mm Hg) with regard to the primary outcome measure of in-hospital mortality in both the TBI and traumatic shock cohorts. Multiple logistic regression was used to calculate odds ratios (ORs) after adjustment for multiple covariables. In addition, regression spline curves were generated to estimate the risk of death as a continuous function of PaO₂ levels. A total of 1248 TBI patients were included, of whom 396 (32%) died before hospital discharge. Associations between hypoxemia and increased mortality (OR, 1.8; 95% confidence interval [CI], 1.2-2.8; p = 0.008) and between hyperoxemia and decreased mortality (OR, 0.6; 95% CI, 0.4-0.9; p = 0.018) were observed. A total of 582 traumatic shock patients were included, of whom 52 (9%) died before hospital discharge. No statistically significant associations were observed between in-hospital mortality and either hypoxemia (OR, 1.0; 95% CI, 0.4-2.4; p = 0.987) or hyperoxemia (OR, 1.9; 95% CI, 0.6-5.7; p = 0.269). Among patients with severe TBI but not traumatic shock, hypoxemia was associated with an increase of in-hospital mortality and hyperoxemia was associated with a decrease of in-hospital mortality.

Pre-hospital tracheal intubation in severe traumatic brain injury: a systematic review and meta-analysis

BACKGROUND

Severe traumatic brain injury (TBI) continues to be a leading cause of death, particularly in young adults. Severe TBI contributes to significant socioeconomic burden secondary to the long-term disability, impacting the individual and their family, and wider society. The aim of this study was to determine whether establishing a pre-hospital definitive airway was beneficial to mortality and morbidity when compared with no pre-hospital airway.

METHODS

A literature search for all relevant studies was performed in Medline, Embase, Cochrane, EBSCO, and Emcare databases, with studies comparing effects of pre-hospital tracheal intubation vs noninvasive airway management on mortality in non-paediatric patients with severe TBI. There were 1025 studies that had abstracts screened from this search. This study was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

We identified 19 studies that met inclusion criteria. The included studies identified no significant difference in mortality between pre-hospital and no pre-hospital tracheal intubation, with an odds ratio of 1.07 (95% CI, 0.72-1.57; P<0.001). The meta-analysis identified a trend favouring pre-hospital tracheal intubation with respect to long-term morbidity, with an odds ratio of 0.92 (95% CI, 0.51-1.67; P<0.001).

CONCLUSIONS

Management of traumatic brain injuries is a constantly evolving field, with ever-changing target parameters regarding management. There is growing evidence, based on the RCTs and recent studies, that pre-hospital tracheal intubation in patients with severe TBI is beneficial if performed by well-trained, experienced practitioners in accordance with current TBI guidelines.

PROSPERO REGISTRATION

CRD42021234439.

A systematic review of the timing of intubation in patients with traumatic brain injury: pre-hospital versus in-hospital intubation

PURPOSE

The objective of this systematic review was to examine current evidence on the risks versus benefit of pre-hospital intubation when compared with in-hospital intubation in adult patients with traumatic brain injuries.

METHODS

We conducted electronic searches of PubMed, Medline, Embase, CIANHL and the Cochrane library up to March 2021. Data extracted compared mortality, length of hospital and intensive care stay, pneumonia and functional outcomes in traumatic brain injured patients undergoing pre-hospital intubation versus in-hospital intubation. The risk of bias was assessed using the Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

Ten studies including 25,766 patients were analysed. Seven were retrospective studies, two prospective cohort studies and one randomised control study. The mean mortality rate in patients who underwent pre-hospital intubation was 44.5% and 31.98% for in-hospital intubation. The odds ratio for an effect of pre-hospital intubation on mortality ranged from 0.31 (favouring in-hospital intubation) to 3.99 (favouring pre-hospital). The overall quality of evidence is low; however, the only randomised control study showed an improved functional outcome for pre-hospital intubation at 6 months.

CONCLUSIONS

The existing evidence does not support widespread pre-hospital intubation in all traumatic brain injured patients. This does not, however, contradict the need for the intervention when there is severe airway compromise; instead, it must be assessed by experienced personnel if a time critical transfer to hospital is more advantageous. Favourable neurological outcomes highlighted by the randomised control trial favours pre-hospital intubation, but further research is required in this field.

Brain-Lung Crosstalk: Management of Concomitant Severe Acute Brain Injury and Acute Respiratory Distress Syndrome

Purpose of Review

To summarize pathophysiology, key conflicts, and therapeutic approaches in managing concomitant severe acute brain injury (SABI) and acute respiratory distress syndrome (ARDS).

Recent Findings

ARDS is common in SABI and independently associated with worse outcomes in all SABI subtypes. Most landmark ARDS trials excluded patients with SABI, and evidence to guide decisions is limited in this population. Potential areas of conflict in the management of patients with both SABI and ARDS are (1) risk of intracranial pressure (ICP) elevation with high levels of positive end-expiratory pressure (PEEP), permissive hypercapnia due to lung protective ventilation (LPV), or prone ventilation; (2) balancing a conservative fluid management strategy with ensuring adequate cerebral perfusion, particularly in patients with symptomatic vasospasm or impaired cerebrovascular blood flow; and (3) uncertainty about the benefit and harm of corticosteroids in this population, with a mortality benefit in ARDS, increased mortality shown in TBI, and conflicting data in other SABI subtypes. Also, the widely adapted partial pressure of oxygen (PaO2) target of > 55 mmHg for ARDS may exacerbate secondary brain injury, and recent guidelines recommend higher goals of 80-120 mmHg in SABI. Distinct pathophysiology and trajectories among different SABI subtypes need to be considered.

Summary

The management of SABI with ARDS is highly complex, and conventional ARDS management strategies may result in increased ICP and decreased cerebral perfusion. A crucial aspect of concurrent management is to recognize the risk of secondary brain injury in the individual patient, monitor with vigilance, and adjust management during critical time windows. The care of these patients requires meticulous attention to oxygenation and ventilation, hemodynamics, temperature management, and the neurological exam. LPV and prone ventilation should be utilized, and supplemented with invasive ICP monitoring if there is concern for cerebral edema and increased ICP. PEEP titration should be deliberate, involving measures of hemodynamic, pulmonary, and brain physiology. Serial volume status assessments should be performed in SABI and ARDS, and fluid management should be individualized based on measures of brain perfusion, the neurological exam, and cardiopulmonary status. More research is needed to define risks and benefits in corticosteroids in this population.

Association of Pre-Hospital Helicopter Transport with Reduced Mortality in Traumatic Brain Injury in Japan: A Nationwide Retrospective Cohort Study

Patients with traumatic brain injury (TBI) are severely injured patients who require timely, efficient, and specialized care. The effectiveness of helicopter emergency medical services (HEMS) for patients with TBI remains unclear. This study aimed to compare the mortality of patients with TBI transported by HEMS and ground ambulance using propensity score-matching analysis, and to analyze the effects of HEMS in various subpopulations. We conducted a retrospective analysis of the Japan Trauma Data Bank. The study period was from January 2004 to December 2018. The participants were divided into two groups: the helicopter group (patients transported by HEMS) and ground group (patients transported by ground ambulance). The principal outcome was death at hospital discharge. In total, 58,532 patients were eligible for analysis (ground group, n = 54,820 [93.7%]; helicopter group, n = 3712 [6.3%]). Helicopter transport decreased patient mortality at hospital discharge (adjusted odds ratio [OR], 0.83; 95% confidence interval [CI], 0.74-0.92). In propensity score-matched patients, the proportion of deaths at hospital discharge was lower in the helicopter (18.76%) than in the ground (21.21%) group (crude OR, 0.86; 95% CI, 0.77-0.96). The mortality rate in the helicopter group was significantly reduced in many subpopulations, especially in cases of severe TBI with a decreased level of consciousness or higher Injury Severity Score (ISS; Japan Coma Scale score 2 [adjusted OR, 0.60; 95% CI, 0.45-0.80] and ISS ≥50 [adjusted OR, 0.69; 95% CI, 0.48-0.99]). Although the study design was non-randomized, our findings in patients with TBI showed that HEMS conferred a mortality benefit over ground ambulance.

Establishing quality indicators for prehospital advanced airway management: a modified nominal group technique consensus process

Background

Pre-hospital advanced airway management is a complex intervention composed of numerous steps, interactions, and variables that can be delivered to a high standard in the pre-hospital setting. Standard research methods have struggled to evaluate this complex intervention because of considerable heterogeneity in patients, providers, and techniques. In this study, we aimed to develop a set of quality indicators to evaluate pre-hospital advanced airway management.

Methods

We used a modified nominal group technique consensus process comprising three email rounds and a consensus meeting among a group of 16 international experts. The final set of quality indicators was assessed for usability according to the National Quality Forum Measure Evaluation Criteria.

Results

Seventy-seven possible quality indicators were identified through a narrative literature review with a further 49 proposed by panel experts. A final set of 17 final quality indicators composed of three structure-, nine process-, and five outcome-related indicators, was identified through the consensus process. The quality indicators cover all steps of pre-hospital advanced airway management from preoxygenation and use of rapid sequence induction to the ventilatory state of the patient at hospital delivery, prior intubation experience of provider, success rates and complications.

Conclusions

We identified a set of quality indicators for pre-hospital advanced airway management that represent a practical tool to measure, report, analyse, and monitor quality and performance of this complex intervention.

PaCO2-management in the neuro-critical care of patients with subarachnoid hemorrhage

The partial pressure of carbon dioxide (PaCO2) in the arterial blood is a strong vasomodulator affecting cerebral blood flow and the risk of cerebral edema and ischemia after acute brain injury. In turn, both complications are related to poor outcome in patients with aneurysmal subarachnoid hemorrhage (aSAH). We aimed to analyze the effect of PaCO2 levels on the course and outcome of aSAH. All patients of a single institution treated for aSAH over 13.5 years were included (n = 633). Daily PaCO2 values from arterial blood gas measurements were recorded for up to 2 weeks after ictus. The study endpoints were: delayed cerebral ischemia (DCI), need for decompressive craniectomy due to increased intracranial pressure > 20 mmHg refractory to conservative treatment and poor outcome at 6-months follow-up (modified Rankin scale > 2). By correlations with the study endpoints, clinically relevant cutoffs for the 14-days mean values for the lowest and highest daily PaCO2 levels were defined by receiver operating characteristic curve analysis. Association with the study endpoints for the identifies subgroups was analyzed using multivariate analysis. The optimal range for PaCO2 values was identified between 30 and 38 mmHg. ASAH patients with poor initial condition (WFNS 4/5) were less likely to show PaCO2 values within the range of 30-38 mmHg (p < 0.001, OR = 0.44). In the multivariate analysis, PaCO2 values between 30 and 38 mmHg were associated with a lower risk for decompressive craniectomy (p = 0.042, aOR = 0.27), DCI occurrence (p = 0.035; aOR = 0.50), and poor patient outcome (p = 0.004; aOR = 0.42). The data from this study shows an independent positive association between low normal mean PaCO2 values during the acute phase of aSAH and patients' outcome. This effect might be attributed to the reduction of intracranial hypertension and alterations in the cerebral blood flow.

Optimal Targets of the First 24-h Partial Pressure of Carbon Dioxide in Patients with Cerebral Injury: Data from the MIMIC-III and IV Database

BACKGROUND

It is generally believed that hypercapnia and hypocapnia will cause secondary injury to patients with craniocerebral diseases, but a small number of studies have shown that they may have potential benefits. We assessed the impact of partial pressure of arterial carbon dioxide (PaCO₂) on in-hospital mortality of patients with craniocerebral diseases. The hypothesis of this research was that there is a nonlinear correlation between PaCO₂ and in-hospital mortality in patients with craniocerebral diseases and that mortality rate is the lowest when PaCO₂ is in a normal range.

METHODS

We identified patients with craniocerebral diseases from Medical Information Mart for Intensive Care third and fourth edition databases. Cox regression analysis and restricted cubic splines were used to examine the association between PaCO₂ and in-hospital mortality.

RESULTS

Nine thousand six hundred and sixty patients were identified. A U-shaped association was found between the first 24-h PaCO₂ and in-hospital mortality in all participants. The nadir for in-hospital mortality risk was estimated to be at 39.5 mm Hg (p for nonlinearity < 0.001). In the subsequent subgroup analysis, similar results were found in patients with traumatic brain injury, metabolic or toxic encephalopathy, subarachnoid hemorrhage, cerebral infarction, and other encephalopathies. Besides, the mortality risk reached a nadir at PaCO₂ in the range of 35-45 mm Hg. The restricted cubic splines showed a U-shaped association between the first 24-h PaCO₂ and in-hospital mortality in patients with other intracerebral hemorrhage and cerebral tumor. Nonetheless, nonlinearity tests were not statistically significant. In addition, Cox regression analysis showed that PaCO₂ ranging 35-45 mm Hg had the lowest death risk in most patients. For patients with hypoxic-ischemic encephalopathy and intracranial infections, the first 24-h PaCO₂ and in-hospital mortality did not seem to be correlated.

CONCLUSIONS

Both hypercapnia and hypocapnia are harmful to most patients with craniocerebral diseases. Keeping the first 24-h PaCO₂ in the normal range (35-45 mm Hg) is associated with lower death risk.

Association of Ventilation during Initial Trauma Resuscitation for Traumatic Brain Injury and Post-Traumatic Outcomes: A Systematic Review

OBJECTIVES

In the absence of evidence of acute cerebral herniation, normal ventilation is recommended for patients with traumatic brain injury (TBI). Despite this recommendation, ventilation strategies vary during the initial management of patients with TBI and may impact outcome. The goal of this systematic review was to define the best evidence-based practice of ventilation management during the initial resuscitation period.

METHODS

A literature search of PubMed, CINAHL, and SCOPUS identified studies from 2009 through 2019 addressing the effects of ventilation during the initial post-trauma resuscitation on patient outcomes.

RESULTS

The initial search yielded 899 articles, from which 13 were relevant and selected for full-text review. Six of the 13 articles met the inclusion criteria, all of which reported on patients with TBI. Either end-tidal carbon dioxide (ETCO2) or partial pressure carbon dioxide (PCO2) were the independent variables associated with mortality. Decreased rates of mortality were reported in patients with normal PCO2 or ETCO2.

CONCLUSIONS

Normoventilation, as measured by ETCO2 or PCO2, is associated with decreased mortality in patients with TBI. Preventing hyperventilation or hypoventilation in patients with TBI during the early resuscitation phase could improve outcome after TBI.

End-tidal to arterial carbon dioxide gradient is associated with increased mortality in patients with traumatic brain injury: a retrospective observational study

Early definitive airway protection and normoventilation are key principles in the treatment of severe traumatic brain injury. These are currently guided by end tidal CO2 as a proxy for PaCO2. We assessed whether the difference between end tidal CO2 and PaCO2 at hospital admission is associated with in-hospital mortality. We conducted a retrospective observational cohort study of consecutive patients with traumatic brain injury who were intubated and transported by Helicopter Emergency Medical Services to a Level 1 trauma center between January 2014 and December 2019. We assessed the association between the CO2 gap-defined as the difference between end tidal CO2 and PaCO2-and in-hospital mortality using multivariate logistic regression models. 105 patients were included in this study. The mean ± SD CO2 gap at admission was 1.64 ± 1.09 kPa and significantly greater in non-survivors than survivors (2.26 ± 1.30 kPa vs. 1.42 ± 0.92 kPa, p < .001). The correlation between EtCO2 and PaCO2 at admission was low (Pearson's r = .287). The mean CO2 gap after 24 h was only 0.64 ± 0.82 kPa, and no longer significantly different between non-survivors and survivors. The multivariate logistic regression model showed that the CO2 gap was independently associated with increased mortality in this cohort and associated with a 2.7-fold increased mortality for every 1 kPa increase in the CO2 gap (OR 2.692, 95% CI 1.293 to 5.646, p = .009). This study demonstrates that the difference between EtCO2 and PaCO2 is significantly associated with in-hospital mortality in patients with traumatic brain injury. EtCO2 was significantly lower than PaCO2, making it an unreliable proxy for PaCO2 when aiming for normocapnic ventilation. The CO2 gap can lead to iatrogenic hypoventilation when normocapnic ventilation is aimed and might thereby increase in-hospital mortality.

Lung-protective ventilation and adjunctive strategies to manage respiratory failure: are they safe in the neurological patient?

PURPOSE OF REVIEW

The coexistence of neurological injury and respiratory failure is common in intensive care. This article provides a contemporary overview of the safety and efficacy of different strategies for mechanical ventilation and adjunctive respiratory approaches in patients with acute brain injury.

RECENT FINDINGS

Available evidence indicates that lung-protective ventilation (LPV) can be implemented safely in a range of patients with concurrent respiratory failure and brain injury of different etiologies; however, the clinical efficacy of LPV in this setting needs to be established. In patients who have severe acute respiratory distress syndrome (ARDS) and brain injury, adjunctive measures (neuromuscular blocker drug infusions, prone positioning, extracorporeal membrane oxygenation) may be considered, although the neurophysiological impact and safety of these techniques need further investigation. Intracranial pressure and other neuromonitoring techniques may be of value to ensure optimal management of mechanical ventilation and adjunctive measures in this population.

SUMMARY

Research is needed to determine the safety, feasibility, and efficacy of LPV and adjunctive approaches for managing patients with concurrent brain injury and respiratory failure.

Evolution Over Time of Ventilatory Management and Outcome of Patients With Neurologic Disease

OBJECTIVES

To describe the changes in ventilator management over time in patients with neurologic disease at ICU admission and to estimate factors associated with 28-day hospital mortality.

DESIGN

Secondary analysis of three prospective, observational, multicenter studies.

SETTING

Cohort studies conducted in 2004, 2010, and 2016.

PATIENTS

Adult patients who received mechanical ventilation for more than 12 hours.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Among the 20,929 patients enrolled, we included 4,152 (20%) mechanically ventilated patients due to different neurologic diseases. Hemorrhagic stroke and brain trauma were the most common pathologies associated with the need for mechanical ventilation. Although volume-cycled ventilation remained the preferred ventilation mode, there was a significant (p < 0.001) increment in the use of pressure support ventilation. The proportion of patients receiving a protective lung ventilation strategy was increased over time: 47% in 2004, 63% in 2010, and 65% in 2016 (p < 0.001), as well as the duration of protective ventilation strategies: 406 days per 1,000 mechanical ventilation days in 2004, 523 days per 1,000 mechanical ventilation days in 2010, and 585 days per 1,000 mechanical ventilation days in 2016 (p < 0.001). There were no differences in the length of stay in the ICU, mortality in the ICU, and mortality in hospital from 2004 to 2016. Independent risk factors for 28-day mortality were age greater than 75 years, Simplified Acute Physiology Score II greater than 50, the occurrence of organ dysfunction within first 48 hours after brain injury, and specific neurologic diseases such as hemorrhagic stroke, ischemic stroke, and brain trauma.

CONCLUSIONS

More lung-protective ventilatory strategies have been implemented over years in neurologic patients with no effect on pulmonary complications or on survival. We found several prognostic factors on mortality such as advanced age, the severity of the disease, organ dysfunctions, and the etiology of neurologic disease.

Effect of Implementing the Out-of-Hospital Traumatic Brain Injury Treatment Guidelines: The Excellence in Prehospital Injury Care for Children Study (EPIC4Kids)

STUDY OBJECTIVE

We evaluate the effect of implementing the out-of-hospital pediatric traumatic brain injury guidelines on outcomes in children with major traumatic brain injury.

METHODS

The Excellence in Prehospital Injury Care for Children study is the preplanned secondary analysis of the Excellence in Prehospital Injury Care study, a multisystem, intention-to-treat study using a before-after controlled design. This subanalysis included children younger than 18 years who were transported to Level I trauma centers by participating out-of-hospital agencies between January 1, 2007, and June 30, 2015, throughout Arizona. The primary and secondary outcomes were survival to hospital discharge or admission for children with major traumatic brain injury and in 3 subgroups, defined a priori as those with moderate, severe, and critical traumatic brain injury. Outcomes in the preimplementation and postimplementation cohorts were compared with logistic regression, adjusting for risk factors and confounders.

RESULTS

There were 2,801 subjects, 2,041 in preimplementation and 760 in postimplementation. The primary analysis (postimplementation versus preimplementation) yielded an adjusted odds ratio of 1.16 (95% confidence interval 0.70 to 1.92) for survival to hospital discharge and 2.41 (95% confidence interval 1.17 to 5.21) for survival to hospital admission. In the severe traumatic brain injury cohort (Regional Severity Score-Head 3 or 4), but not the moderate or critical subgroups, survival to discharge significantly improved after guideline implementation (adjusted odds ratio = 8.42; 95% confidence interval 1.01 to 100+). The improvement in survival to discharge among patients with severe traumatic brain injury who received positive-pressure ventilation did not reach significance (adjusted odds ratio = 9.13; 95% confidence interval 0.79 to 100+).

CONCLUSION

Implementation of the pediatric out-of-hospital traumatic brain injury guidelines was not associated with improved survival when the entire spectrum of severity was analyzed as a whole (moderate, severe, and critical). However, both adjusted survival to hospital admission and discharge improved in children with severe traumatic brain injury, indicating a potential severity-based interventional opportunity for guideline effectiveness. These findings support the widespread implementation of the out-of-hospital pediatric traumatic brain injury guidelines.

The effects of arterial CO2 on the injured brain: Two faces of the same coin

Serum levels of carbon dioxide (CO₂) closely regulate cerebral blood flow (CBF) and actively participate in different aspects of brain physiology such as hemodynamics, oxygenation, and metabolism. Fluctuations in the partial pressure of arterial CO₂ (PaCO₂) modify the aforementioned variables, and at the same time influence physiologic parameters in organs such as the lungs, heart, kidneys, and the gastrointestinal tract. In general, during acute brain injury (ABI), maintaining normal PaCO₂ is the target to be achieved. Both hypercapnia and hypocapnia may comprise secondary insults and should be avoided during ABI. The risks of hypocapnia mostly outweigh the potential benefits. Therefore, its therapeutic applicability is limited to transient and second-stage control of intracranial hypertension. On the other hand, inducing hypercapnia could be beneficial when certain specific situations require increasing CBF. The evidence supporting this claim is very weak. This review attempts providing an update on the physiology of CO₂, its risks, benefits, and potential utility in the neurocritical care setting.

Evaluating a novel formula for noninvasive estimation of arterial carbon dioxide during post-resuscitation care

BACKGROUND

Controlling arterial carbon dioxide is paramount in mechanically ventilated patients, and an accurate and continuous noninvasive monitoring method would optimize management in dynamic situations. In this study, we validated and further refined formulas for estimating partial pressure of carbon dioxide with respiratory gas and pulse oximetry data in mechanically ventilated cardiac arrest patients.

METHODS

A total of 4741 data sets were collected retrospectively from 233 resuscitated patients undergoing therapeutic hypothermia. The original formula used to analyze the data is PaCO₂ -est1 = PETCO₂  + k[(PIO₂  - PETCO₂ ) - PaO₂ ]. To achieve better accuracy, we further modified the formula to PaCO₂ -est2 = k₁ *PETCO₂  + k₂ *(PIO₂  - PETCO₂ ) + k₃ *(100-SpO₂ ). The coefficients were determined by identifying the minimal difference between the measured and calculated arterial carbon dioxide values in a development set. The accuracy of these two methods was compared with the estimation of the partial pressure of carbon dioxide using end-tidal carbon dioxide.

RESULTS

With PaCO₂ -est1, the mean difference between the partial pressure of carbon dioxide, and the estimated carbon dioxide was 0.08 kPa (SE ±0.003); with PaCO₂ -est2 the difference was 0.036 kPa (SE ±0.009). The mean difference between the partial pressure of carbon dioxide and end-tidal carbon dioxide was 0.72 kPa (SE ±0.01). In a mixed linear model, there was a significant difference between the estimation using end-tidal carbon dioxide and PaCO₂ -est1 (P < .001) and PaCO₂ -est2 (P < .001) respectively.

CONCLUSIONS

This novel formula appears to provide an accurate, continuous, and noninvasive estimation of arterial carbon dioxide.

Association of systemic secondary brain insults and outcome in patients with convulsive status epilepticus: A post hoc study of a randomized controlled trial

OBJECTIVE

To evaluate the association between systemic factors (mean arterial blood pressure, arterial partial pressures of carbon dioxide and oxygen, body temperature, natremia, and glycemia) on day 1 and neurologic outcomes 90 days after convulsive status epilepticus.

METHODS

This was a post hoc analysis of the Evaluation of Therapeutic Hypothermia in Convulsive Status Epilepticus in Adults in Intensive Care (HYBERNATUS) multicenter open-label controlled trial, which randomized 270 critically ill patients with convulsive status epilepticus requiring mechanical ventilation to therapeutic hypothermia (32°C-34°C for 24 hours) plus standard care or standard care alone between March 2011 and January 2015. The primary endpoint was a Glasgow Outcome Scale score of 5, defining a favorable outcome, 90 days after convulsive status epilepticus.

RESULTS

The 172 men and 93 women had a median age of 57 years (45-68 years). Among them, 130 (49%) had a history of epilepsy, and 59 (29%) had a primary brain insult. Convulsive status epilepticus was refractory in 86 (32%) patients, and total seizure duration was 67 minutes (35-120 minutes). The 90-day outcome was unfavorable in 126 (48%) patients. In multivariate analysis, none of the systemic secondary brain insults were associated with outcome; achieving an unfavorable outcome was associated with age >65 years (odds ratio [OR] 2.17, 95% confidence interval [CI] 1.20-3.85; p = 0.01), refractory convulsive status epilepticus (OR 2.00, 95% CI 1.04-3.85; p = 0.04), primary brain insult (OR 2.00, 95% CI 1.02-4.00; p = 0.047), and no bystander-witnessed seizure onset (OR 2.49, 95% CI 1.05-5.59; p = 0.04).

CONCLUSIONS

In our population, systemic secondary brain insults were not associated with outcome in critically ill patients with convulsive status epilepticus.

CLINICALTRIALSGOV IDENTIFIER

NCT01359332.

Hypothermia as an adjuvant treatment in paediatric refractory or super-refractory status epilepticus

Therapeutic hypothermia is among the adjuvant therapies suggested for refractory or super-refractory status epilepticus (R/SR-SE) in paediatric patients. Experimental evidence of neuroprotective and antiseizure effects provides a strong rationale for using therapeutic hypothermia in patients with status epilepticus. Thus, hypothermia between 20°C and 33°C in animals with status epilepticus is associated not only with significantly less neuronal damage, predominantly in the hippocampal CA1, CA2, and CA3 areas, but also with increased seizure latency and decreased seizure frequency and duration. Therapeutic hypothermia has rarely been used in paediatric R/SR-SE. In the few reported cases, seizure control was markedly improved but nearly half the patients experienced recurrences after rewarming. Studies are needed to clarify the modalities and indications of therapeutic hypothermia in paediatric patients with R/SR-SE. WHAT THIS PAPER ADDS: Hypothermia at 20°C to 33°C is neuroprotective and has antiseizure effects in experimental status epilepticus. In children, antiseizure effects are marked but recurrences after rewarming are common.

Current Status of Indications, Timing, Management, Complications, and Outcomes of Tracheostomy in Traumatic Brain Injury Patients

Tracheostomy is the commonest bedside surgical procedure performed on patients needing mechanical ventilation with traumatic brain injury (TBI). The researchers made an effort to organize a narrative review of the indications, timing, management, complications, and outcomes of tracheostomy in relation to neuronal and brain-injured patients following TBI. The study observations were collated from the published literature, namely original articles, book chapters, case series, randomized studies, systematic reviews, and review articles. Information sorting was restricted to tracheostomy and its association with TBI. Care was taken to review the correlation of tracheostomy with clinical correlates including indications, scheduling, interventions, prognosis, and complications of the patients suffering from mild, moderate and severe TBIs using Glasgow Coma Scale, Glasgow Outcome Scale, intraclass correlation coefficient, and other internationally acclaimed outcome scales. Tracheostomy is needed to overcome airway obstruction, prolonged respiratory failure and as indispensable component of mechanical ventilation due to diverse reasons in intensive care unit. Researchers are divided over early tracheostomy or late tracheostomy from days to weeks. The conventional classic surgical technique of tracheostomy has been superseded by percutaneous techniques by being less invasive with lesser complications, classified into early and late complications that may be life threatening. Additional studies have to be conducted to validate and streamline varied observations to frame evidence-based practice for successful weaning and decannulation. Tracheostomy is a safer option in critically ill TBI patients for which a universally accepted protocol for tracheostomy is needed that can help to optimize indications and outcomes.

Hyperventilation in neurological patients: from physiology to outcome evidence

Hyperventilation is commonly used in neurological patients to decrease elevated intracranial pressure (ICP) or relax a tense brain. However, the potentially deleterious effects of hyperventilation may limit its clinical application. The aim of this review is to summarize the physiological and outcome evidence related to hyperventilation in neurological patients.

Association of Statewide Implementation of the Prehospital Traumatic Brain Injury Treatment Guidelines With Patient Survival Following Traumatic Brain Injury: The Excellence in Prehospital Injury Care (EPIC) Study

Importance

Traumatic brain injury (TBI) is a massive public health problem. While evidence-based guidelines directing the prehospital treatment of TBI have been promulgated, to our knowledge, no studies have assessed their association with survival.

Objective

To evaluate the association of implementing the nationally vetted, evidence-based, prehospital treatment guidelines with outcomes in moderate, severe, and critical TBI.

Design, Setting, and Participants

The Excellence in Prehospital Injury Care (EPIC) Study included more than 130 emergency medical services systems/agencies throughout Arizona. This was a statewide, multisystem, intention-to-treat study using a before/after controlled design with patients with moderate to critically severe TBI (US Centers for Disease Control and Prevention Barell Matrix-Type 1 and/or Abbreviated Injury Scale Head region severity ≥3) transported to trauma centers between January 1, 2007, and June 30, 2015. Data were analyzed between October 25, 2017, and February 22, 2019.

Interventions

Implementation of the prehospital TBI guidelines emphasizing avoidance/treatment of hypoxia, prevention/correction of hyperventilation, and avoidance/treatment of hypotension.

Main Outcomes and Measures

Primary: survival to hospital discharge; secondary: survival to hospital admission.

Results

Of the included patients, the median age was 45 years, 14 666 (67.1%) were men, 7181 (32.9%) were women; 16 408 (75.1% ) were white, 1400 (6.4%) were Native American, 743 (3.4% ) were Black, 237 (1.1%) were Asian, and 2791 (12.8%) were other race/ethnicity. Of the included patients, 21 852 met inclusion criteria for analysis (preimplementation phase [P1]: 15 228; postimplementation [P3]: 6624). The primary analysis (P3 vs P1) revealed an adjusted odds ratio (aOR) of 1.06 (95% CI, 0.93-1.21; P = .40) for survival to hospital discharge. The aOR was 1.70 (95% CI, 1.38-2.09; P < .001) for survival to hospital admission. Among the severe injury cohorts (but not moderate or critical), guideline implementation was significantly associated with survival to discharge (Regional Severity Score-Head 3-4: aOR, 2.03; 95% CI, 1.52-2.72; P < .001; Injury Severity Score 16-24: aOR, 1.61; 95% CI, 1.07-2.48; P = .02). This was also true for survival to discharge among the severe, intubated subgroups (Regional Severity Score-Head 3-4: aOR, 3.14; 95% CI, 1.65-5.98; P < .001; Injury Severity Score 16-24: aOR, 3.28; 95% CI, 1.19-11.34; P = .02).

Conclusions and Relevance

Statewide implementation of the prehospital TBI guidelines was not associated with significant improvement in overall survival to hospital discharge (across the entire, combined moderate to critical injury spectrum). However, adjusted survival doubled among patients with severe TBI and tripled in the severe, intubated cohort. Furthermore, guideline implementation was significantly associated with survival to hospital admission. These findings support the widespread implementation of the prehospital TBI treatment guidelines.

Trial Registration

ClinicalTrials.gov identifier: NCT01339702.

The European guideline on management of major bleeding and coagulopathy following trauma: fifth edition

BACKGROUND

Severe traumatic injury continues to present challenges to healthcare systems around the world, and post-traumatic bleeding remains a leading cause of potentially preventable death among injured patients. Now in its fifth edition, this document aims to provide guidance on the management of major bleeding and coagulopathy following traumatic injury and encourages adaptation of the guiding principles described here to individual institutional circumstances and resources.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004, and the current author group included representatives of six relevant European professional societies. The group applied a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were re-examined and revised based on scientific evidence that has emerged since the previous edition and observed shifts in clinical practice. New recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated.

RESULTS

Advances in our understanding of the pathophysiology of post-traumatic coagulopathy have supported improved management strategies, including evidence that early, individualised goal-directed treatment improves the outcome of severely injured patients. The overall organisation of the current guideline has been designed to reflect the clinical decision-making process along the patient pathway in an approximate temporal sequence. Recommendations are grouped behind the rationale for key decision points, which are patient- or problem-oriented rather than related to specific treatment modalities. While these recommendations provide guidance for the diagnosis and treatment of major bleeding and coagulopathy, emerging evidence supports the author group's belief that the greatest outcome improvement can be achieved through education and the establishment of and adherence to local clinical management algorithms.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. If incorporated into local practice, these clinical practice guidelines have the potential to ensure a uniform standard of care across Europe and beyond and better outcomes for the severely bleeding trauma patient.

Association of abnormal carbon dioxide levels with poor neurological outcomes in aneurysmal subarachnoid hemorrhage: a retrospective observational study

Background

In patients with aneurysmal subarachnoid hemorrhage (SAH), an association between hypocapnia and poor clinical outcomes has been reported. However, the optimal arterial carbon dioxide tension (PaCO₂) remains unknown. The present retrospective study aimed to examine the association of abnormal PaCO₂ levels with neurological outcomes and investigate the optimal target PaCO₂ level in patients with SAH.

Methods

We retrospectively selected consecutive adult patients hospitalized in the intensive care unit (ICU) for SAH between January 2009 and April 2017. Univariate and multivariate analyses were performed to identify the independent predictors of unfavorable neurological outcomes (i.e., modified Rankin scale score of 3–6 on hospital discharge).

Results

Among 158 patients with SAH, 73 had unfavorable neurological outcomes. During the first 2 weeks in the ICU, the median number of PaCO₂ measurements per patient was 43. The factors significantly associated with unfavorable neurological outcomes were age, Hunt and Kosnik grade, maximum lactate levels during the first 24 h, and maximum (odds ratio [OR], 1.12; 95% confidence interval [CI], 1.03–1.21; p < 0.01) and minimum PaCO₂ levels (OR, 0.81; 95% CI, 0.72–0.92; p < 0.01). Receiver operating characteristic curve analysis revealed that the cutoff range of PaCO₂ was 30.2–48.3 mmHg. Unfavorable neurological outcomes were noted in 78.8% of patients with PaCO₂ levels outside this range and in 22.8% of patients with PaCO₂ levels within this range.

Conclusions

Both the maximum and minimum PaCO₂ levels during ICU management in patients with SAH were significantly associated with unfavorable neurological outcomes. Further prospective studies are required to validate our findings and explore their clinical implications. Our findings may provide a scientific rationale for these future prospective studies.

Electronic supplementary material

The online version of this article (10.1186/s40560-018-0353-1) contains supplementary material, which is available to authorized users.

Airway management in pre-hospital critical care: a review of the evidence for a 'top five' research priority

The conduct and benefit of pre-hospital advanced airway management and pre-hospital emergency anaesthesia have been widely debated for many years. In 2011, prehospital advanced airway management was identified as a ‘top five’ in physician-provided pre-hospital critical care. This article summarises the evidence for and against this intervention since 2011 and attempts to address some of the more controversial areas of this topic.

Emergency Neurological Life Support: Airway, Ventilation, and Sedation

Airway management and ventilation are central to the resuscitation of the neurologically ill. These patients often have evolving processes that threaten the airway and adequate ventilation. Furthermore, intubation, ventilation, and sedative choices directly affect brain perfusion. Therefore, Airway, Ventilation, and Sedation was chosen as an Emergency Neurological Life Support protocol. Topics include airway management, when and how to intubate with special attention to hemodynamics and preservation of cerebral blood flow, mechanical ventilation settings and the use of sedative agents based on the patient's neurological status.

Association of Hypercapnia and Hypercapnic Acidosis With Clinical Outcomes in Mechanically Ventilated Patients With Cerebral Injury

IMPORTANCE

Clinical studies investigating the effects of hypercapnia and hypercapnic acidosis in acute cerebral injury are limited. The studies performed so far have mainly focused on the outcomes in relation to the changes in partial pressure of carbon dioxide and pH in isolation and have not evaluated the effects of partial pressure of carbon dioxide and pH in conjunction.

OBJECTIVE

To review the association of compensated hypercapnia and hypercapnic acidosis during the first 24 hours of intensive care unit admission on hospital mortality in adult mechanically ventilated patients with cerebral injury.

DESIGN, SETTING, AND PARTICIPANTS

Multicenter, binational retrospective review of patients with cerebral injury (traumatic brain injury, cardiac arrest, and stroke) admitted to 167 intensive care units in Australia and New Zealand between January 2000 and December 2015. Patients were classified into 3 groups based on combination of arterial pH and arterial carbon dioxide (normocapnia and normal pH, compensated hypercapnia, and hypercapnic acidosis) during the first 24 hours of intensive care unit stay.

MAIN OUTCOMES AND MEASURES

Hospital mortality.

RESULTS

A total of 30 742 patients (mean age, 55 years; 21 827 men [71%]) were included. Unadjusted hospital mortality rates were highest in patients with hypercapnic acidosis. Multivariable logistic regression analysis and Cox proportional hazards analysis in 3 diagnostic categories showed increased odds of hospital mortality (cardiac arrest odds ratio [OR], 1.51; 95% CI, 1.34-1.71; stroke OR, 1.43; 95% CI, 1.27-1.6; and traumatic brain injury OR, 1.22; 95% CI, 1.06-1.42; P <.001) and hazard ratios (HR) (cardiac arrest HR, 1.23; 95% CI, 1.14-1.34; stroke HR, 1.3; 95% CI, 1.21-1.4; traumatic brain injury HR, 1.13; 95% CI, 1-1.27), in patients with hypercapnic acidosis compared with normocapnia and normal pH. There was no difference in mortality between patients who had compensated hypercapnia compared with patients who had normocapnia and normal pH. In patients with hypercapnic acidosis, the adjusted OR of hospital mortality increased with increasing partial pressure of carbon dioxide, while no such increase was noted in patients with compensated hypercapnia.

CONCLUSIONS AND RELEVANCE

Hypercapnic acidosis was associated with increased risk of hospital mortality in patients with cerebral injury. Hypercapnia, when compensated to normal pH during the first 24 hours of intensive care unit admission, may not be harmful in mechanically ventilated patients with cerebral injury.

Respiratory Management in Patients with Severe Brain Injury

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency Medicine 2018. Other selected articles can be found online at https://www.biomedcentral.com/collections/annualupdate2018 . Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901 .

Association Between Partial Pressure of Arterial Carbon Dioxide and Survival to Hospital Discharge Among Patients Diagnosed With Sepsis in the Emergency Department

OBJECTIVE

The objective of this study was to test the association between the partial pressure of arterial carbon dioxide and survival to hospital discharge among mechanically ventilated patients diagnosed with sepsis in the emergency department.

DESIGN

Retrospective cohort study of a single center trial registry.

SETTING

Academic medical center.

PATIENTS

Mechanically ventilated emergency department patients.

INCLUSION CRITERIA

age 18 years and older, diagnosed with sepsis in the emergency department, and mechanical ventilation initiated in the emergency department.

INTERVENTIONS

Arterial blood gases obtained after initiation of mechanical ventilation were analyzed. The primary outcome was survival to hospital discharge. We tested the association between partial pressure of arterial carbon dioxide and survival using multivariable logistic regression adjusting for potential confounders. Sensitivity analyses, including propensity score matching were also performed.

MEASUREMENTS AND MAIN RESULTS

Six hundred subjects were included, and 429 (72%) survived to hospital discharge. The median (interquartile range) partial pressure of arterial carbon dioxide was 42 (34-53) mm Hg for the entire cohort and 44 (35-57) and 39 (31-45) mm Hg among survivors and nonsurvivors, respectively (p < 0.0001 Wilcox rank-sum test). On multivariable analysis, a 1 mm Hg rise in partial pressure of arterial carbon dioxide was associated with a 3% increase in odds of survival (adjusted odds ratio, 1.03; 95% CI, 1.01-1.04) after adjusting for tidal volume and other potential confounders. These results remained significant on all sensitivity analyses.

CONCLUSION

In this sample of mechanically ventilated sepsis patients, we found an association between increasing levels of partial pressure of arterial carbon dioxide and survival to hospital discharge. These findings justify future studies to determine the optimal target partial pressure of arterial carbon dioxide range for mechanically ventilated sepsis patients.

Body Temperature after EMS Transport: Association with Traumatic Brain Injury Outcomes

INTRODUCTION

Low body temperatures following prehospital transport are associated with poor outcomes in patients with traumatic brain injury (TBI). However, a minimal amount is known about potential associations across a range of temperatures obtained immediately after prehospital transport. Furthermore, a minimal amount is known about the influence of body temperature on non-mortality outcomes. The purpose of this study was to assess the correlation between temperatures obtained immediately following prehospital transport and TBI outcomes across the entire range of temperatures.

METHODS

This retrospective observational study included all moderate/severe TBI cases (CDC Barell Matrix Type 1) in the pre-implementation cohort of the Excellence in Prehospital Injury Care (EPIC) TBI Study (NIH/NINDS: 1R01NS071049). Cases were compared across four cohorts of initial trauma center temperature (ITCT): <35.0°C [Very Low Temperature (VLT)]; 35.0-35.9°C [Low Temperature (LT)]; 36.0-37.9°C [Normal Temperature (NT)]; and ≥38.0°C [Elevated Temperature (ET)]. Multivariable analysis was performed adjusting for injury severity score, age, sex, race, ethnicity, blunt/penetrating trauma, and payment source. Adjusted odds ratios (aORs) with 95% confidence intervals (CI) for mortality were calculated. To evaluate non-mortality outcomes, deaths were excluded and the adjusted median increase in hospital length of stay (LOS), ICU LOS and total hospital charges were calculated for each ITCT group and compared to the NT group.

RESULTS

22,925 cases were identified and cases with interfacility transfer (7361, 32%), no EMS transport (1213, 5%), missing ITCT (2083, 9%), or missing demographic data (391, 2%) were excluded. Within this study cohort the aORs for death (compared to the NT group) were 2.41 (CI: 1.83-3.17) for VLT, 1.62 (CI: 1.37-1.93) for LT, and 1.86 (CI: 1.52-3.00) for ET. Similarly, trauma center (TC) LOS, ICU LOS, and total TC charges increased in all temperature groups when compared to NT.

CONCLUSION

In this large, statewide study of major TBI, both ETs and LTs immediately following prehospital transport were independently associated with higher mortality and with increased TC LOS, ICU LOS, and total TC charges. Further study is needed to identify the causes of abnormal body temperature during the prehospital interval and if in-field measures to prevent temperature variations might improve outcomes.

Initial arterial carbon dioxide tension is associated with neurological outcome after resuscitation from cardiac arrest

STUDY OBJECTIVES

To determine the relationships between partial pressure of arterial carbon dioxide (PaCO₂), prescribed minute ventilation (MV), and neurologic outcome in patients resuscitated from cardiac arrest.

METHODS

This was a retrospective cohort study utilizing a multicenter database of adult patients with return of spontaneous circulation (ROSC) after cardiac arrest. The primary outcome was neurologic status at hospital discharge, defined by Cerebral Performance Category (CPC) score: CPC 1-2 was favorable, CPC 3-5 was poor. We compared rates of initial normocarbia (PaCO₂ 31-49mmHg) and mean sequential PaCO₂ measurements obtained over the first 24h. We also assessed the influence of MV on the PaCO₂ at initial, 6, 12, 18, and 24h after cardiac arrest using univariate linear regression.

RESULTS

One hundred and fourteen patients from 3 institutions met inclusion criteria. Overall, 46/114 (40.4%, 95% CI: 31.4-49.4%) patients survived to hospital discharge, and 33/114 (28.9%, 20.6-37.2%) had CPC 1-2 at the time of discharge. A total of 38.9% (95% CI: 29.9-47.9%) of patients had initial normocarbia; 43.2% (28.6-57.8%) of these patients were discharged with CPC 1-2, compared with 20.3% (10.8-29.8%) of dyscarbic patients. By 6h, neurologic outcomes were not significantly associated with PaCO₂. Prescribed MV was not associated with PaCO₂ at any time point with the exception of a weak correlation at hour 18.

CONCLUSION

Initial normocarbia was associated with favorable neurological outcome in patients resuscitated from cardiac arrest. This relationship was not seen at subsequent time points. There was no significant association between prescribed MV and PaCO₂ or neurologic outcome.

The Effect of Combined Out-of-Hospital Hypotension and Hypoxia on Mortality in Major Traumatic Brain Injury

STUDY OBJECTIVE

Survival is significantly reduced by either hypotension or hypoxia during the out-of-hospital management of major traumatic brain injury. However, only a handful of small studies have investigated the influence of the combination of both hypotension and hypoxia occurring together. In patients with major traumatic brain injury, we evaluate the associations between mortality and out-of-hospital hypotension and hypoxia separately and in combination.

METHODS

All moderate or severe traumatic brain injury cases in the preimplementation cohort of the Excellence in Prehospital Injury Care study (a statewide, before/after, controlled study of the effect of implementing the out-of-hospital traumatic brain injury treatment guidelines) from January 1, 2007, to March 31, 2014, were evaluated (exclusions: <10 years, out-of-hospital oxygen saturation ≤10%, and out-of-hospital systolic blood pressure <40 or >200 mm Hg). The relationship between mortality and hypotension (systolic blood pressure <90 mm Hg) or hypoxia (saturation <90%) was assessed with multivariable logistic regression, controlling for Injury Severity Score, head region severity, injury type (blunt versus penetrating), age, sex, race, ethnicity, payer, interhospital transfer, and trauma center.

RESULTS

Among the 13,151 patients who met inclusion criteria (median age 45 years; 68.6% men), 11,545 (87.8%) had neither hypotension nor hypoxia, 604 (4.6%) had hypotension only, 790 (6.0%) had hypoxia only, and 212 (1.6%) had both hypotension and hypoxia. Mortality for the 4 study cohorts was 5.6%, 20.7%, 28.1%, and 43.9%, respectively. The crude and adjusted odds ratios for death within the cohorts, using the patients with neither hypotension nor hypoxia as the reference, were 4.4 and 2.5, 6.6 and 3.0, and 13.2 and 6.1, respectively. Evaluation for an interaction between hypotension and hypoxia revealed that the effects were additive on the log odds of death.

CONCLUSION

In this statewide analysis of major traumatic brain injury, combined out-of-hospital hypotension and hypoxia were associated with significantly increased mortality. This effect on survival persisted even after controlling for multiple potential confounders. In fact, the adjusted odds of death for patients with both hypotension and hypoxia were more than 2 times greater than for those with either hypotension or hypoxia alone. These findings seem supportive of the emphasis on aggressive prevention and treatment of hypotension and hypoxia reflected in the current emergency medical services traumatic brain injury treatment guidelines but clearly reveal the need for further study to determine their influence on outcome.

Airway management and mechanical ventilation in acute brain injury

Patients with acute neurologic disease often develop respiratory failure, the management of which profoundly affects brain physiology and long-term functional outcomes. This chapter reviews airway management and mechanical ventilation of patients with acute brain injury, offering practical strategies to optimize treatment of respiratory failure and minimize secondary brain injury. Specific concerns that are addressed include physiologic changes during intubation and ventilation such as the effects on intracranial pressure and brain perfusion; cervical spine management during endotracheal intubation; the role of tracheostomy; and how ventilation and oxygenation are utilized to minimize ischemia-reperfusion injury and cerebral metabolic distress.

Apneic oxygenation is associated with a reduction in the incidence of hypoxemia during the RSI of patients with intracranial hemorrhage in the emergency department

Critically ill patients undergoing emergent intubation are at risk of oxygen desaturation during the management of their airway. Patients with intracranial hemorrhage (ICH) are particularly susceptible to the detrimental effects of hypoxemia. Apneic oxygenation (AP OX) may be able to reduce the occurrence of oxygen desaturation during the emergent intubation of these patients. We sought to assess the effect AP OX on oxygen desaturation during the rapid sequence intubation (RSI) of patients with ICH in the emergency department (ED). We prospectively collected data on all patients intubated in an urban academic ED over the 2-year period from July 1, 2013 to June 30, 2015. Following each intubation, the operator completed a standardized continuous quality improvement (CQI) data form, which included information on patient, operator and intubation characteristics. Operators recorded data on the use of AP OX, the oxygen flow rate used for AP OX, and the starting and lowest saturations during intubation. Adult patients with ICH who underwent RSI by emergency medicine (EM) residents were included in the analyses. The primary outcome variable was any oxygen saturation <90 % during the intubation. We performed a backward stepwise multivariate logistic regression analysis to identify variables associated with oxygen desaturation. The primary independent variable of interest was the use of AP OX during the intubation. Inclusion criteria for the study was met by 127 patients. AP OX was used in 72 patients (AP OX group) and was not used in 55 patients (NO AP OX group). The incidence of desaturation was 5/72 (7 %) in the AP OX group and was 16/55 (29 %) in the NO AP OX group. In the multivariate logistic regression analysis the use of AP OX was associated with a reduced odds of desaturation (aOR 0.13; 95 % CI 0.03-0.53). Patients with ICH who received AP OX during RSI in the ED were seven times less likely to have an oxygen saturation of <90 % during the intubation compared to patients who did not receive AP OX. AP OX is a simple intervention that may minimize the risk of oxygen desaturation during the RSI of patients with ICH.

Ventilatory Management of the Noninjured Lung

This article reviews aspects of mechanical ventilation in patients without lung injury, patients in the perioperative period, and those with neurologic injury or disease including spinal cord injury. Specific emphasis is placed on ventilator strategies, including timing and indications for tracheostomy. Lung protective ventilation, using low tidal volumes and modest levels of positive end-expiratory pressure, should be the default consideration in all patients requiring mechanical ventilatory support. The exception may be the patient with high cervical spinal cord injuries who requires mechanical ventilatory support. There is no consensus on the timing of tracheostomy in patients with neurologic diseases.

Emergency Neurological Life Support: Airway, Ventilation, and Sedation

Airway management and ventilation are central to the resuscitation of the neurologically ill. These patients often have evolving processes that threaten the airway and adequate ventilation. Furthermore, intubation, ventilation, and sedative choices directly affect brain perfusion. Therefore, airway, ventilation, and sedation was chosen as an emergency neurological life support protocol. Topics include airway management, when and how to intubate with special attention to hemodynamics and preservation of cerebral blood flow, mechanical ventilation settings, and the use of sedative agents based on the patient's neurological status.

Academic Emergency Medicine Physicians' Knowledge of Mechanical Ventilation

Introduction

Although emergency physicians frequently intubate patients, management of mechanical ventilation has not been emphasized in emergency medicine (EM) education or clinical practice. The objective of this study was to quantify EM attendings’ education, experience, and knowledge regarding mechanical ventilation in the emergency department.

Methods

We developed a survey of academic EM attendings’ educational experiences with ventilators and a knowledge assessment tool with nine clinical questions. EM attendings at key teaching hospitals for seven EM residency training programs in the northeastern United States were invited to participate in this survey study. We performed correlation and regression analyses to evaluate the relationship between attendings’ scores on the assessment instrument and their training, education, and comfort with ventilation.

Results

Of 394 EM attendings surveyed, 211 responded (53.6%). Of respondents, 74.5% reported receiving three or fewer hours of ventilation-related education from EM sources over the past year and 98 (46%) reported receiving between 0–1 hour of education. The overall correct response rate for the assessment tool was 73.4%, with a standard deviation of 19.9. The factors associated with a higher score were completion of an EM residency, prior emphasis on mechanical ventilation during one’s own residency, working in a setting where an emergency physician bears primary responsibility for ventilator management, and level of comfort with managing ventilated patients. Physicians’ comfort was associated with the frequency of ventilator changes and EM management of ventilation, as well as hours of education.

Conclusion

EM attendings report caring for mechanically ventilated patients frequently, but most receive fewer than three educational hours a year on mechanical ventilation, and nearly half receive 0–1 hour. Physicians’ performance on an assessment tool for mechanical ventilation is most strongly correlated with their self-reported comfort with mechanical ventilation.

The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition

BACKGROUND

Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013.

RESULTS

The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.

Brain tissue partial pressure of oxygen predicts the outcome of severe traumatic brain injury under mild hypothermia treatment

OBJECTIVE

The aim of this study was to investigate the clinical significance and changes of brain tissue partial pressure of oxygen (PbtO2) in the course of mild hypothermia treatment (MHT) for treating severe traumatic brain injury (sTBI).

METHODS

There were 68 cases with sTBI undergoing MHT. PbtO2, intracranial pressure (ICP), jugular venous oxygen saturation (SjvO2), and cerebral perfusion pressure (CPP) were continuously monitored, and clinical outcomes were evaluated using the Glasgow Outcome Scale score.

RESULTS

Of 68 patients with sTBI, PbtO2, SjvO2, and CPP were obviously increased, but decreased ICP level was observed throughout the MHT. PbtO2 and ICP were negatively linearly correlated, while there was a positive linear correlation between PbtO2 and SjvO2. Monitoring CPP and SjvO2 was performed under normal circumstances, and a large proportion of patients were detected with low PbtO2. Decreased PbtO2 was also found after MHT.

CONCLUSION

Continuous PbtO2 monitoring could be introduced to evaluate the condition of regional cerebral oxygen metabolism, thereby guiding the clinical treatment and predicting the outcome.

[No improved survival rate in severely injured patients by prehospital intubation : A retrospective data analysis and matched-pair analysis]

BACKGROUND

Training programs for the treatment of trauma patients generally recommend establishing a secure airway if the patient presents with a Glasgow coma scale (GCS) score of less than 9; however, the evidence for its effectiveness is rather sparse. This study analyzed the effect of preclinical intubation on mortality of patients with a GCS <9 in an emergency medical situation.

METHODS

This retrospective analysis included patients who were primarily admitted to a German level 1 trauma center between 2002 and 2012 with an injury severity score (ISS) ≥ 16, a GCS < 9 and primary transport from the site of the accident. Data were collected from the trauma registry of the German Society for Trauma Surgery and from hospital records. A total of 455 patients were included and a matched-pair analysis of 62 patients was conducted.

RESULTS

Both analytical methods showed no significant reduction in mortality rate after prehospital intubation. In the retrospective analysis intubated patients presented with a significantly lower systolic blood pressure on admission, received a higher amount of fluid volume at all phases of treatment and arrived at the hospital after a prolonged rescue time. In the matched-pair analysis, intubated patients also received a higher amount of fluid volume and showed better peripheral oxygen saturation on admission. No further differences between the groups could be found.

CONCLUSION

It appears that preclinical intubation in trauma patients with a GCS < 9 does not result in a better outcome. The preclinical intubation resulted in a reduced systolic blood pressure on arrival at hospital, a prolonged preclinical rescue time and a greater amount of infused fluid volume.